Phosphor-coated glass tubes containing radioactive beta particle-emitting gas, such as tritium gas, provide sources of illumination for displays and the like. Such devices have been utilized extensively, for providing backside illumination for liquid crystal displays in electronic timepieces and calculators.
Pin-point laser beam sources have been utilized in the manufacture of these devices to cut and seal tritium gas-filled tubes. In such manufacturing process, the tritium gas is put into long segments of glass tubing which are then sealed at both ends before the laser sealing and cutting of the tube into shorter segments. This method requires relative movement between the laser beam and tubing. In one system, the laser beam is moved by means of a galvanometer optical system or other system across the glass tubing. In another system, a mechanical system moves the tubing past a fixed laser beam to seal and cut segments from the tubing. These prior art methods have several disadvantages: the galvinometer system which moves and positions the beam is relatively expensive and usually requires the use of a programmable mini-computer. The mechanization required to move the tube past a fixed laser beam is likewise an intricate process requiring relatively expensive and complex equipment and speed control. Furthermore, the process of filling a long segment of glass tubing with tritium gas and sealing both ends prior to sealing and cutting the tubing into smaller segments results in a great variance in the pressure of the gas contained in the cut segments; hence, the brightness is not consistent in the resulting light sources.
It is therefore an object of the present invention to provide an improved method of cutting and sealing gas-filled tubing.
Another object of the invention is to provide an improved method of manufacturing radioactive light sources for illuminating displays and the like.
A further object of the invention is to provide a method of laser beam cutting and sealing gas-filled tubing without the necessity of relative movement between the beam and tubing.
Still another object of the invention is to provide a method for manufacturing radioactive light sources for displays and the like with consistent brightness from each source.
It is another object of the invention to provide an improved apparatus for cutting and sealing gas-filled tubing.
Still another object of the invention is to provide an improved apparatus for the manufacture of radioactive light sources.
It is a further object of the invention to provide a laser beam system for cutting and sealing gas-filled tubing without relative movement between the beam and the tubing.
Yet another object of the invention is to provide an apparatus for manufacturing improved radioactive light sources.
It is still another object of the invention to provide an apparatus for manufacturing radioactive light sources with consistent brightness.